Ser Gregor Clegane, better known as the Mountain, will be played by Hafþór Júlíus Björnsson in "Game of Thrones" Season 4. Photo: Twitter/Hafþór Júlíus Björnsson

In “Game of Thrones” Season 4, episode 7, “Mockingbird,” the champions for Tyrion’s trial by combat have been named. Representing Tyrion in this heavyweight battle will be Oberyn “The Red Viper” Martell, while Cersei will be represented by Gregor “The Mountain” Clegane.

Warning: Full “Game of Thrones” Season 4 spoilers ahead.

The Mountain’s reputation is well known, from the way he burned and disfigured his brother, the Hound, to the rape and murder of the Red Viper’s sister, Elia Martell. Gregor was last seen in "Game of Thrones" Season 2, raiding the Riverlands and torturing prisoners at Harrenhal. The Mountain is a terrifying individual that’s equal parts brutal and athletic. Ser Gregor Clegane is a massive man, hence his nickname, and it is only fitting the “Game of Thrones” series has cast a strongman to play the role.

Hafþór Júlíus Björnsson, whose nickname is Thor, naturally, will play the Mountain in "Game of Thrones" Season 4, and Gregor makes his first appearance in "Mockingbird."

For the Mountain, this will be the third time the role has been recast. Conan Stevens played the Mountain in "Game of Thrones" Season 1, appearing in "The Wolf and the Lion" and "Cripples, Bastards, and Broken Things." Stevens was replaced by Ian Whyte in "Game of Thrones" Season 2 and while he was tall enough for the role, measuring 7' 1", according to IMDB, but had an athletic build that was not quite imposing enough.

Björnsson definitely fits the role of the Mountain. The strongman from Iceland is 6-foot-9 and weighs 403 pounds, according to his World's Strongest Man profile. Björnsson finished in third place at the 2013 World's Strongest Man competition and was the runner-up in the 2014 World's Strongest Man competition.

The Mountain will take center stage in "Game of Thrones" Season 4, episode 8, "The Mountain and the Viper," and will face the Red Viper in trial by combat. If the Mountain is victorious, Tyrion will be found guilty and if Oberyn wins, Tyrion will be set free.